AAS 195th Meeting, January 2000
Session 7. Galaxy Structures and Dynamics: Models and Observations
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

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[7.07] NGC 7331: Examining Density Wave Contributions in Flocculent Galaxies

D. Bambic (Western Kentucky U.), M. D. Thornley (NRAO)

We have used the VLA in three array configurations (B, C, and D) to produce high-resolution (10\arcsec~and 15\arcsec) HI images of NGC 7331, a nearby flocculent spiral galaxy. In this poster, we compare the distribution and kinematics of atomic hydrogen in NGC 7331 with the results of a previous kinematic analysis of H\alpha Fabry-Perot data (Marcelin et al. 1994). Marcelin et al. suggest that perturbations in the velocity field of NGC 7331 are consistent with the presence of density waves, despite the lack of grand-design spiral structure in the optical. We find significant, organized velocity perturbations are present, though we do not detect velocity perturbations in the inner region Marcelin et al. indicated, likely due to our lower resolution. However, the more complete coverage of our map provides us with a more complete picture of the kinematic structures present over the optical disk of NGC 7331.

We will also compare our results with an HI kinematic study of NGC 5055, a similarly flocculent spiral galaxy which has previously been shown to exhibit density-wave-like velocity perturbations in its optically flocculent disk (Thornley & Mundy 1997). We discuss the implications of our findings on the theory of spiral density waves and the significance of separate classifications for disk galaxies with apparent flocculent and grand design spiral structure.

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